710 
CAPTAIN F. W. BEECHEY ON THE TIDAL STREAMS OF 
3n the rota- 
ory motion 
)f the stream. 
5xplanation 
)f Plan 1, 
^late XL, 
Dn the time 
iv’hen the 
stream 
ittains its 
maximum 
rate. 
North Sea, as those of Mons. Monnier were on the border of the mixed tide of the 
other sea. These authors have been followed by other talented men, until a common 
opinion was gaining ground that streams in general had a rotatory motion. 
Had the observers above-mentioned made their observations anywhere between 
the Start and Beachy Head, or between Cromer and the North Foreland, a different 
result would have been obtained ; for in all this space, occupying nearly 360 miles in 
extent, the stream runs steadily throughout both tides, scarcely changing its direc- 
tion for four hours and upwards, and then only preparatory to going round to the 
new coming tide. 
Upon Plan 1, Plate XL. I have given examples of the streams in question. The 
upper figures represent the revolving tides, exactly in the order in whieh the ob- 
servations were made, on a direct line between the Texel and Cromer. The circular 
arrows show the direction in which the stream revolves, and the figures against the 
arrows the times before and after high water in which the streams run in those direc- 
tions. The second line of revolving tides was observed in the mixed tides off the 
Start, and is similar to those off the Texel. The lower lines are samples of the 
steadiness of the stream which prevails throughout the ordinary tides of the Channel; 
the stations are given exactly as they occurred on a parallel of 52° 15' N., which 
nearly intersects the position Professor Whewell has assigned to the node of the 
North Sea tide, and as they were observed in the English Channel between Portland 
and Beachy Head. 
It was in the upper or revolving streams that the late Captain Hewitt’s observa- 
tions were made, and in the second row, or similar tides, that M. Monnier and 
Captain White made their observations ; and there can no longer be any doubt that 
the rotatory tides are the exceptions to the general courses of the stream, and not the 
rule. 
The time at which the stream attains its maximum rate in the Channel is another 
point of interest and of importance to the seaman. In the ‘ Pilote Frangaise’ we find 
numerous observations carefully drawn out, and all giving nearly the same result, 
which is to place the strongest part of the stream at high and low water, and the 
slack water at half-tide. In ‘ Memoire sur les Courants de la Manche,’ before re- 
ferred to, we read at p. 15, “On conclura de ce qui vient d’etre dit que I’heure de la 
haute mer doit coincider avec celle ou le courant de dot acquiert sa plus grand 
vitesse On concevra de la meme maniere que le courant de jusant doit atteindre 
sa plus grand vitesse au moment de la basse mer and in a work of high au- 
thority published in this country, it is stated, doubtless from the authorities before- 
mentioned, that “ in mid channel the motion of the water will be flowing most rapidly 
up the Channel at the time of high water, and its motion upwards will cease when 
the water has dropped to its mean height.” 
This idea of M. Monnier, viz. of the strongest part of the stream occurring at 
high water on the shore, is part of the same error which the author before quoted had 
